The purpose of this project is to improve our understanding of ways in which drugs may alter centrally mediated neurotransmission and to develop better pharmacotherapies for neurological disorders. Topics currently under investigation include: (1) the role of the striatonigral pathway, dopaminergic autoreceptors and substantia nigra pars reticulata neurons in regulation of the activity of nigrostriatal dopamine neurons; (2) the function gamma aminobutyric acid (GABA) afferents to the substantia nigra; (3) effects of potential dopamine agonists and GABA-mimetic agents on the function of identified neurons in the basal ganglia; (4) mechanisms involved in endogenous regulation of glutamic acid decarboxylase (GAD).